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CVE Record

CVE-2025-39909: mm/damon/lru_sort: avoid divide-by-zero in damon_lru_sort_apply_parameters()

In the Linux kernel, the following vulnerability has been resolved: mm/damon/lru_sort: avoid divide-by-zero in damon_lru_sort_apply_parameters() Patch series "mm/damon: avoid divide-by-zero in DAMON module's parameters application". DAMON's RECLAIM and LRU_SORT modules perform no validation on user-configured parameters during application, which may lead to division-by-zero errors. Avoid the divide-by-zero by adding validation checks when DAMON modules attempt to apply the parameters. This patch (of 2): During the calculation of 'hot_thres' and 'cold_thres', either 'sample_interval' or 'aggr_interval' is used as the divisor, which may lead to division-by-zero errors. Fix it by directly returning -EINVAL when such a case occurs. Additionally, since 'aggr_interval' is already required to be set no smaller than 'sample_interval' in damon_set_attrs(), only the case where 'sample_interval' is zero needs to be checked.

UnknownCVSS not scoredNot KEV-listedUpdated
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Glexia's TakeAutomated analysisunknown

Security readout for executives and security teams

Plain-English summary

CVE-2025-39909 is a Linux kernel bug in DAMON LRU_SORT parameter handling. Invalid user-configured timing parameters can cause divide-by-zero errors. The public record does not provide CVSS, CWE, or confirmed exploitation. Treat it as a kernel stability issue requiring normal patch management, especially where DAMON modules are enabled or configurable.

Executive priority

Prioritize through standard kernel patch cycles unless local evidence shows DAMON exposure on critical systems. There is no sourced active exploitation, but kernel stability issues can affect availability and should not remain untracked.

Technical view

DAMON RECLAIM and LRU_SORT lacked validation when applying parameters. In LRU_SORT, hot_thres and cold_thres calculations can use sample_interval or aggr_interval as divisors. The fix returns -EINVAL when sample_interval is zero, relying on damon_set_attrs() to enforce aggr_interval >= sample_interval.

Likely exposure

Exposure is likely limited to Linux systems running affected kernel versions where DAMON LRU_SORT or related DAMON module parameters can be configured. The supplied data lists Linux as affected and references stable kernel fixes. Confirm exact distro package exposure with vendor advisories.

Exploitation context

The sources describe a parameter-validation flaw, not a confirmed remote attack path. KEV is false, and no cited source reports active exploitation. Evidence is insufficient to claim exploit availability, privilege requirements, or real-world abuse.

Researcher notes

Focus review on DAMON parameter validation and downstream backports. The public record names divide-by-zero risk during parameter application but omits CVSS, CWE, exploitability details, and privilege assumptions. Avoid treating affected version metadata as complete without vendor confirmation.

Mitigation direction

  • Apply Linux kernel updates that include the referenced stable fixes.
  • Check Debian and other distro advisories for fixed package versions.
  • Restrict DAMON module parameter changes to trusted administrators.
  • Review vendor guidance before using compensating controls as substitutes for patching.

Validation and detection

  • Inventory Linux kernel versions across servers and workloads.
  • Identify systems using DAMON RECLAIM, LRU_SORT, or related configuration paths.
  • Map deployed kernels to the referenced stable commits or distro fixed packages.
  • Confirm monitoring shows no recurring kernel faults around DAMON parameter application.
Prepared
Confidence
medium
Sources
8

Public sources used

Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.

Potential ATT&CK relevance

Conservative CVE-to-ATT&CK context

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CVE-2025-39909 mapping review

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Vulnerability profileCVE Program record
Severity
Unknown
CVSS
Not scored
Known Exploited
No
Published
Official CVE source material

CNA and ADP enrichment extracted from CVE v5

These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.

0CVSS vectors
3Timeline events
1ADP providers
7Source links

Vulnerability timeline

Timeline events are normalized from CVE metadata, CNA source timelines, ADP timelines, and KEV metadata when present.

  1. CVE reservedCVE Program

    The CVE ID was reserved by the assigning CNA.

  2. CVE publishedCVE Program

    The CVE record was published.

  3. CVE updatedCVE Program

    The CVE record metadata indicates this as the latest update time.

ADP provider summaries

CVECVE Program Container

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
LinuxLinux40e983cca9274e177bd5b9379299b44d9536ac68, 40e983cca9274e177bd5b9379299b44d9536ac68, 40e983cca9274e177bd5b9379299b44d9536ac68, 40e983cca9274e177bd5b9379299b44d9536ac68, 40e983cca9274e177bd5b9379299b44d9536ac68unaffected
LinuxLinux6.0, 0, 6.1.153, 6.6.107, 6.12.48, 6.16.8, 6.17affected
Weakness

CWE details

No CWE listed

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